The key is:
I think you are looking for this discussion ‘Show documentation tooltips as in jupyter notebook 6.*’ and follow-up? Unfortunately, that post doesn’t link to the related, posted issue report at the conclusion, but you can find it here.
For insight, Jupyter Notebook 7+ is built on JupyterLab components and so a lot of the features and abilities match JupyterLab now, which is said in relation to this specific topic in the bottom of this related issue post ’ Open the help in a bottom panel #6692’ and includes related images that illustrate the situation you are stating in your post:
“Jupyter Notebook 7 does the same as JupyterLab since it uses the same notebook component:”